1. Field of the Invention
This invention pertains to sighting devices which are secured to a turret or other heavy piece of equipment which rotates in response to changes in direction of the sight. More particularly, the invention pertains to a vehicular mounted TOW missile system which holds the base of the sighting unit relatively stationary about its axis of rotation to simulate the operation of a ground-mounted TOW missile system.
2. Description of the Prior Art
It is well established that the TOW (tube launched optically tracked, wire command, link guided) missile system of the type described in United States Army Technical Manual TM 9-1425-470-12, January, 1974, is a proven and perhaps unequalled system for tracking accuracy. The system uses a manually operated, viscous damped, position control, weapon pointing system. The system is generally mounted on a tripod which is stationary on the ground or on a vehicle with a post that is fixed to the vehicle and with the vehicle stationary on the ground. The operator then in sighting walks around the tripod or post with the missile launch tube being connected to the sight and thus movable directly therewith. The sighting mechanism has a day sight which is spaced vertically from a night sight and is also provided with an infrared sensing sight aligned with the day sight. Basically the operation of the missile system requires that the operator locate the cross hairs of one of the optical sights on the moving target and fires the missile. The operator then maintains the cross hairs on the target by moving the sight either elevationally or rotationally in traverse with the infrared sensing sight locating the missile and sending control signals to the missile to direct the missile from its initially fired direction to a corrected direction corresponding to the direction indicated by the cross hairs of the optical sight.
It is desirable to mount a missile weapon system on a vehicle in a manner in which the operator is completely protected by heavy armor plate. That is, it is desirable to mount such a TOW missile system in a personnel carrier or a tank and preferably to mount it within the conventional rotatable turret in the vehicle. Most modern vehicular-mounted gun controls, such as presently in tanks, however are "rate" control systems as compared to the TOW weapon "position" control system. In a rate system the operator displaces his controls by an amount required to generate a turret turning velocity equivalent to the apparent velocity of the target. Thus, when tracking a constant speed target, the controls would be held displaced but stationary. As the target accelerated the control would also be moved to achieve a more rapid turning rate of the turret and if the target decelerated while traveling still in the same direction, the control would have to be retracted back by movement in a direction opposite to the direction of movement of the target. Unfortunately, rate control systems have been shown to be less accurate for the TOW type missile launcher then position control systems for the TOW type; missile launcher. Additionally, it requires extensive training to convert an experienced TOW operator from a position control operator to a rate control operator.